Bimetallic MOF derived nickel nanoclusters supported by nitrogen-doped carbon for efficient electrocatalytic CO₂ reduction

Utilizing electrocatalytic CO2 reduction (ECR) to decrease the carbon footprint has been regarded as a promising pathway. Herein, we report the synthesis of Ni nanoclusters (NCs) of below 2 nm highly dispersed on N-doped carbon using a Ni/Zn bimetallic metal-organic framework (MOF) precursor. The size and the content of the Ni catalyst can be effectively controlled by varying the Ni:Zn ratio in MOF precursors. The −NH2 group in MOF ligand critically influences the size of Ni catalyst, as well as the property of the carbon substrate. At the optimum ratio of 1:150, Ni NCs with an average size of 1.9 nm anchored on pyridinic N-rich carbon were obtained after MOF pyrolysis. The resultant catalyst exhibits a high Faradaic efficiency for CO (FECO, 98.7%) and considerable partial current density for CO (JCO, −40.4 mA·cm−2) at −0.88 V versus reversible hydrogen electrode (RHE). Benefiting from the synergistic effect of small Ni clusters and their optimal interaction with the carbon support, the catalyst displays exceptional long-term stability. Density functional theory (DFT) calculations carried out for the three model structures confirm that Ni NCs anchored on N-doped carbon facilitate the easier formation of *COOH intermediate and faster electron transfer rate compared with the large-sized Ni particles represented by Ni(111) and the N-doped carbon without Ni.Nanyang Technological UniversityNational Research Foundation (NRF)This work is supported by Nanyang Technological University and the Singapore National Research Foundation (NRF) under its Campus for Research Excellence and Technological Enterprise (CREATE) program through the Cambridge Center for Advanced Research and Education in Singapore (CARES) Cambridge Center for Carbon Reduction in Chemical Technology (C4T) and through CARES and the Berkeley Educational Alliance for Research in Singapore (BEARS) eCO2P program. X. D. W. acknowledge the financial support from Natural Science Foundation of Jiangsu Province (No. BK20200711)

Temperature-induced low-coordinate Ni single-atom catalyst for boosted CO₂ electroreduction activity

Single-atom catalysts (SACs) exhibit remarkable potential for electrochemical reduction of CO2 to value-added products. However, the commonly pursued methods for preparing SACs are hard to scale up, and sometimes, lack general applicability because of expensive raw materials and complex synthetic procedures. In addition, the fine tuning of coordination environment of SACs remains challenging due to their structural vulnerability. Herein, a simple and universal strategy is developed to fabricate Ni SACs with different nitrogen coordination numbers through one-step pyrolysis of melamine, Ni(NO3 )∙6H2 O, and polyvinylpyrrolidone at different temperatures. Experimental measurements and theoretical calculations reveal that the low-coordinate Ni SACs exhibit outstanding CO2 reduction performance and stability, achieving a Faradic efficiency (FECO ) of 98.5% at -0.76 V with CO current density of 24.6 mA cm-2 , and maintaining FECO of over 91.0% at all applied potential windows from -0.56 to -1.16 V, benefiting from its coordinatively unsaturated structure to afford high catalytic activity and low barrier for the formation of *COOH intermediate. No significant performance degradation is observed over 50 h of continuous operation. Additionally, several other metallic single-atom catalysts are successfully prepared by this synthetic method, demonstrating the universality of this strategy.Nanyang Technological UniversityNational Research Foundation (NRF)This work is supported by the National Natural Science Foundation of China (NSFC) (No. 22105178, 52103237), the Nanyang Technological University, and the National Research Foundation (NRF), Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program through the Carbon Reduction in Chemical Technology (C4T) program

In Situ Preparation of Thermotropic Liquid Crystalline Polyester and Nylon 10T

Poly-decamethylene terephthalamide (PA10T) is one of high temperature special engineering plastics, which is widely used in aviation automobile, and electronic industries. However, its bad processability, poor crystallinity, and toughness may affect its further applications. In this work, the melting polycondensation synthesis of thermotropic liquid crystalline polyester (TLCP) prepolymer was explored. This synthesized TLCP was then added into PA10T via in-situ compounding, to obtain the polydecamethylene terephthalamide / thermotropic liquid crystalline polyester composites (TLCP/PA10T). The TLCP was found easy to be oriented, which can reduce the entanglement of PA10T and improve the processing properties of PA10T. Moreover, the anisotropy under tensile conditions after the TLCP orientation can form microfibers and improve the mechanical properties of the composites. The relationship between crystallization properties, tensile strength and TLCP content of TLCP/PA10T composites was also studied. Such TLCP/PA10T composites can serve as a high temperature special engineering plastic in industrial manufacturing

Flame synthesized blue TiO₂₋ₓ with tunable oxygen vacancies from surface to grain boundary to bulk

Fabrication of nonstoichiometric metal oxides containing oxygen vacancies (OVs) has been an effective strategy to modulate their (photo)catalytic or (photo)electrochemical performances which are all affected by charge transfer at the interface and in the bulk. Considerable efforts are still needed to achieve tunability of OVs, as well as their quantitative characterization. Herein, a one-step flame synthesis method is reported for the first time for fast fabrication of blue TiO2- x with controllable defect content and location. Temperature-programmed oxidation (TPO) analysis is applied for the first time and found to be an excellent technique in both differentiating and quantifying OVs at the surface, grain boundary (GB), and bulk of TiO2- x . The results indicate that a moderate level of OVs can greatly enhance the charge transfer. Importantly, the OVs locked at GBs due to the thermal sintering of nanoparticles during the synthesis can facilitate the anchoring and reduction of Pt species.National Research Foundation (NRF)This work was financially supported by National Research Foundation through the Cambridge Centre for Carbon Reduction in Chemical Technology (C4T) CREATE Programme

Fire-retardant effect of titania-polyurea coating and additional enhancement via aromatic diamine and modified melamine polyphosphate

Polymeric materials and composites are well suited to support structures in marine conditions due to their corrosion resistance. However, their low glass transition temperature makes them vulnerable to softening at high temperatures. Hence, fire retardancy is a key aspect if these materials are selected to ensure stiffness under flammable conditions. In this paper, a fire-retardant polyurea coating for industrial applications is proposed. The aromatic diamine and aliphatic diisocyanate are believed to have a synergistic effect in improving flame properties. Moreover, various combinations of flame-retardant additives with aromatic and aliphatic-based polyurea are mixed to further improve fire-retardancy. Through the characterizations of their glass transition temperature and delay in the ignition, it indicates that the combination of Talc and melamine polyphosphate may provide an outstanding enhancement for the Titania-polyurea coating, and such enhancement may improve its original tensile and compression strength, and surface hardness as well.Ministry of Education (MOE)Published versionThis research was funded by MOE Academic Research Fund (AcRF) Tier 1 Project “Nano-structured Titania with tunable hydrophilic/hydrophobic behavior and photocatalytic function for marine structure application”, Grant Call (Call 1/2018) _MSE (EP Code EP5P, Project ID 122018-T1-001-077), Ministry of Education (MOE), Singapore